1. Field of the Invention
The present invention relates to a plating apparatus and a plating method for plating a substrate such as a semiconductor wafer with copper.
2. Description of Related Art
In the production of a semiconductor device, a plating process is often performed for plating one surface of a semiconductor wafer (hereinafter referred to simply as “wafer”). Plating apparatuses for the plating of the wafer are required to perform complicated process steps and to provide a high-quality metal film by the plating. Since the composition of a plating liquid changes during repetition of the plating process, the plating liquid should periodically be analyzed and adjusted so as to be kept in a predetermined composition on the basis of the results of the analysis. This requires a time-consuming and troublesome operation.
The plating liquid contains minor constituents such as a plating accelerating additive, a plating retarding additive, and chlorine which functions to retain the additives on the surface of the wafer. These minor constituents are consumed by the plating. Therefore, the plating process cannot properly be performed unless the minor constituents are added to the plating liquid so as to be kept at proper concentration levels.
However, none of the conventional plating apparatuses are satisfactory in the quality of a film formed by the plating, operability, productivity and the like. Particularly, the conventional plating apparatuses cannot easily and properly manage the minor constituents of the plating liquid, failing to properly perform the plating process.